The anticipated advent of large scale, broad based use of hydrogen as an energy source alternative to fossil fuels brings the anticipation of numerous and widespread hydrogen gas production, storage, transportation, and distribution facilities, any of which can develop leaks. Hydrogen gas is explosive, of course, and a buildup of hydrogen gas in any significant concentration can be dangerous. Various regulations have been developed requiring the use of hydrogen detection devices to detect the presence of hydrogen gas at one volume percent where gaseous hydrogen buildup is possible (29 C.F.R. 1910.106 (1996)) and at 0.4 volume percent for confined spaces (29 C.F.R. 1910.146 (1996)).
Detection of hydrogen gas concentrations by traditional methods, such as mass spectrometers and chromatographs, are accurate but cumbersome. To meet the need for more practical hydrogen gas detectors, attention was directed to semiconductor materials that are sensitive to hydrogen. For example, some transition metal oxides are chemochromic and change color or light absorption and reflection characteristics when exposed to hydrogen, and they were incorporated into portable, wearable detectors that undergo a visible change when in the presence of hydrogen gas. See, for example, U.S. Pat. No. 6,895,805 B2, entitled “Hydrogen Gas Indicator System,” issued to W. Hoagland on May 24, 2005, which is incorporated herein in its entirety.
While such visual hydrogen gas indicator systems have certainly advanced the state of the art in useful hydrogen gas detectors, they still have to be seen to be effective, and someone has to be both present and paying attention whenever hydrogen gas is present, which can be intermittent or transient in some situations. Therefore, better monitoring systems are needed for different environments and situations.